The present invention relates to a peel-apart type instant photographic apparatus using the combination of a negative film and a positive sheet as a supply and, more particularly, to an instant photographic apparatus promoting easy handling of a dark box which receives the supply after the spread of a developer.
A photographic apparatus of the type described in usually operable with a supply in the form of the combination of a negative film and a positive sheet. A peel-apart type instant camera, for example, has a relatively small size and uses a relatively small supply, i.e., small negative film and small positive sheet. Such a negative film and a positive sheet are put on the mark as a pack film. However, when the size of the pack film is increased to extend its applicability to a relatively large-size instant photographic apparatus, it is not easy to handle. It is a common practice with a large-size instant photographic apparatus to separate a negative film and a positive sheet from each other and load each of them in the apparatus in a particular condition. The positive sheet is usually implemented as a positive sheet assembly including a pod filled with a developer, a trap mask for collecting excessive part of the developer having been spread, and other auxiliary parts. On the other hand, the negative film is used in the form of a roll and loaded in a cartridge which is set in the apparatus.
After the negative film has been exposed and then laid on a positive sheet, thye developer sealed in the pod is spread. The joined negative film and positive sheet are left in this condition for a predetermined period of time to effect a developing process. As the predetermined time expires, the negative film is peeled apart from the positive film to end the image forming procedure. A prerequisite with the developing process is that the negative film be sheilded from light until a period of time long enough to protect the resultant image from disturbance even when unexposed silver halide on the photosensitive surface of the negative film receives light expires (about one half or less of the developing time; about 30 seconds to 40 seconds). Some different approaches are available in order to meet the above requirement such as effecting the developing process in a dark place, providing a screening layer (black) on the rear surface of the positive sheet so that the sheet may be left in a light place, and, when the positive sheet is transparent for implementing OHP, dispersing carbon in the developer for shielding light.
When the black screening layer is provided on the rear surface of the positive sheet, a white coating is further provided on the black layer to allow necessary data to be written down and to enhance attractive appearance. The problem with this kind of scheme is, therefore, that the rear surface of the positive sheet bears the color of light gray which is not attractive. The positive sheet has to be provided with a substantial thickness since should it be thin, the black rear surface would show itself on the front surface or image receiving surface to cause the whole image to appear dark. Further, the extra coating on the positive sheet not only increases the cost but also requires the production line to have various complicated implementations such humidity control against curls.
Further, dispersing carbon in the developer is not desirable since carbon degrades color reproducibility. Moreover, in the production aspect, carbon has to be dispersed in a uniform distribution, resulting in the need for complicated production steps.
To eliminate the problems particular to the sheilding schemes of the kind stated above, a dark box may be located downstream of developing rollers for accommodating a supply whose developer has been spread, as proposed in, for example, Japanese Patent Laid-Open Publication No. 76029/1977. With such a dark box, it is possible to fully protect the supply or positive sheet from light without resorting to the traditional light shielding schemes.
The conventional instant photographic apparatus with a dark box, however, has various problems left unsolved, as follows. Since the supply after the spread of the developer is stored in the dark box until the development is fully completed, it occupies the entire appartus body until the development completes (1 minunte to 4 minutes, depending on the film). This increases the waiting time or interval between successive printing operations. The apparatus body is ready to operate even when the supply is left in the dark box. It is likely, therefore, that the operator effects the next printing operation while the development is under way or forgetting to remove the developed supply from the dark box. Then, the expensive negative film and positive sheet are simply wasted. When the development is effected with the lid of the dark box held open, as is likely with the conventional apparatus, the negative sheet and positive sheet are also wasted. Desprite that the developer is apt to smear the dark box and apparatus body, they cannot be readily cleaned since the dark box is incorporated in the apparatus body. The smear would contaminate the rear surface of a positive sheet and/or the operator's hand at the time of next printing operation.